Unravelling the Distribution of Secondary Metabolites in Olea europaea L.: Exhaustive Characterization of Eight Olive-Tree Derived Matrices by Complementary Platforms (LC-ESI/APCI-MS and GC-APCI-MS)

Abstract

In order to understand the distribution of the main secondary metabolites found in Olea europaea L., eight different samples (olive leaf, stem, seed, fruit skin and pulp, as well as virgin olive oil, olive oil obtained from stoned and dehydrated fruits and olive seed oil) coming from a Picudo cv. olive tree were analyzed. All the experimental conditions were selected so as to assure the maximum coverage of the metabolome of the samples under study within a single run. The use of LC and GC with high resolution MS (through different ionization sources, ESI and APCI) and the annotation strategies within MetaboScape 3.0 software allowed the identification of around 150 compounds in the profiles, showing great complementarity between the evaluated methodologies. The identified metabolites belonged to different chemical classes: triterpenic acids and dialcohols, tocopherols, sterols, free fatty acids, and several sub-types of phenolic compounds. The suitability of each platform and polarity (negative and positive) to determine each family of metabolites was evaluated in-depth, finding, for instance, that LC-ESI-MS (+) was the most efficient choice to ionize phenolic acids, secoiridoids, flavonoids and lignans and LC-APCI-MS was very appropriate for pentacyclic triterpenic acids (MS (−)) and sterols and tocopherols (MS (+)). Afterwards, a semi-quantitative comparison of the selected matrices was carried out, establishing their typical features (e.g., fruit skin was pointed out as the matrix with the highest relative amounts of phenolic acids, triterpenic compounds and hydroxylated fatty acids, and seed oil was distinctive for its high relative levels of acetoxypinoresinol and tocopherols).

The use of gamma radiation for extractability improvement of bioactive compounds in olive oil wastes

“…Peaks 3 and 5 presented the same pseudomolecular ion [M-H] − at m/z 377, which fits the oleuropein aglycon (i.e., 3,4-(dihydroxyphenyl)ethanol elenolic acid ester, 3,4-DHPEA-EA). The presence of several oleuropein aglycon derivatives in olive oil and by-products is well reported (Obied et al, 2007;Olmo-García et al, 2018) and explained by the enzymatic loss of the glucose residue of oleuropein and further structural arrangement involving ring opening and keto-enol equilibria during olive oil processing (Obied et al, 2007). Compound 5 shows the same MS 2 fragments as reported by Cardoso et al (2005) for the oleuropein aglycon derivative detected in olive pulp and pomace.…”

“…Up to four compounds with the same mass characteristics were also recovered by Cardinali et al (2012) and Ammar et al (2017) from Olea europaea by-products and identified as β-hydroxyverbascoside diastereoisomers, so that that identity was also assigned the compounds detected herein. Peak 10 presented a pseudomolecular ion [M-H] − at m/z 197 and a fragment ion at m/z 153 (−44 u; loss of a carboxyl residue), which would match syringic acid, a benzoic acid frequently found in olive fruits and byproducts (Obied et al, 2007;Olmo-García et al, 2018), an identity that is given as tentative. A compound with the same pseudomolecular ion as peak 14 ([M-H] − at m/z 337) was detected by Ammar et al (2017) in olive by-products and identified as ascorbyl-hexoside.…”

Evaluating Quality Parameters, the Metabolic Profile, and Other Typical Features of Selected Commercial Extra Virgin Olive Oils from Brazil

“…The importance of some of these minor components is irrefutable; these substances can be used for the appraisal of VOO quality, purity, authenticity, and typicity [ 23 ], and they are linked to the oil’s shelf-life, sensory attributes, and several of its health-promoting effects [ 24 ]. Their determination has traditionally been intricate due to their heterogeneity and relatively low concentrations, but the development of multi-class methods has recently generated great expectations [ 25 , 26 , 27 ], as they can clearly increase the analytical throughput, providing data on a great number of substances within a single analysis.…”

By-Products from Winemaking and Olive Mill Value Chains for the Enrichment of Refined Olive Oil: Technological Challenges and Nutraceutical Features

“…The obtained chromatographic profiles operating in negative ion mode are showed in Figure 2 , while detected compounds are described in Table S1 . Compounds were tentatively identified according to MS and literature data [ 37 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ]. Several substances were not completely identified but based on the MS fragmentation patterns their structure was correlated to some principal skeletons.…”